Test node properties — is_node_properties • ggdag

These functions test various properties of nodes in a DAG:

is_exogenous() tests whether a variable is exogenous (has no parents)
is_instrumental() tests whether a variable is instrumental
is_exposure(), is_outcome(), is_latent() test variable status

Usage

is_exogenous(.dag, .var)

is_instrumental(.dag, .var, exposure = NULL, outcome = NULL)

is_exposure(.dag, .var)

is_outcome(.dag, .var)

is_latent(.dag, .var)

Arguments

.dag: A tidy_dagitty or dagitty object
.var: A character string specifying the variable to test
exposure: A character vector, the exposure variable. Default is NULL, in which case it will be determined from the DAG.
outcome: A character vector, the outcome variable. Default is NULL, in which case it will be determined from the DAG.

Value

A logical value indicating whether the tested property holds

Examples

dag <- dagify(
  y ~ x + z,
  x ~ z,
  exposure = "x",
  outcome = "y",
  latent = "z"
)

is_exogenous(dag, "z")
#> [1] TRUE
is_exposure(dag, "x")
#> [1] TRUE
is_outcome(dag, "y")
#> [1] TRUE
is_latent(dag, "z")
#> [1] TRUE